Jump-spark tester.



P. B. SPOFFORD.

JUMP SPARK TESTER.

APPLICATION FILED FEB. 13,1914.

1 l W?fi7@ u Patenfe June 20, 191i W@w@5$w$;

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jmwwmwmw PERCY B. SPOFFORD, OF HAVERHILL, MASSACHUSETTS.

JUMP-SPARK TESTER.

Specification of Letters Patent.

"atehtcd June 20, 1916.

Applicationfiled February 13, 191%, Serial No. 818,588.

To all whom it may concern .1

Be it known that I, PERCY B. Srorronn, a. citizen of the United States, residing at Havel-hill, in the county of-Essex and State of Massachusetts, have-invented an Improvement in J limp-Spark Testers, of which the following 18 a specification; This 1nvent1on relates to certain improvements in devices known as jump spark test-- ers, 2'. 6., devices which comprise a handle having two projecting contact arms, one of which is adapted to be placed on the spark plug terminal and the other grounded on the engine cylinder, saidcontact arms having terminals held in sulliciently close relation to provide a sparlcgap across which the spark will jump, if a spark also jumps between the plug spark-points. In using said devices I have ascertained that they have but little practical value when used in the daytime, as it is diflicult to see whether a spark is jumping between the terminals of the detector, or not. I have also ascertained that a spark willnot jump the sparkgap under some conditions, as the gap is toO. wide, although the gap should be wide enough to cause a spark which may be readily seen.

The objects of my invention are to provide a detector of the above described type, with which the spark may be as readily seen, in bright sunlight, as in the dark, and which may be conveniently adapted to dilferent conditions or strength of current.

I accomplish these objects by arranging the sparking terminals in an inclosed chamber formed within the handle and providing an aperture through. a wall of the chamber, so arranged that the line of sight therethrough will he directed to the spark-gap, while the spark at this gap will be otherwise shielded from the light, so that the presence of the spark may be readily detected in daylight, and, further, by providing an adjustable sparking terminal on one of the contact arms which will enable the length of the spark-gap to be varied according to conditions.

For a more complete understanding of my invention reference is made to the accompanying drawings, in which,

Figures 1, 2 and 3 are elevations showing diflerent sides of a device, made according to my invention. Fig. a is a. detail sectional view on the line 44t-, of'Fig. 2. 'Fig. 5 is a similar view on the line 5-5 of Fig. 1. i

As shown in the drawing, the handle a has a square end-portion, or holder, to one side of which a plate 6 is secured. A conductor is mounted in said plate, said conductor comprislng a contact arm 0 which extends longitudinally of the handle and a sparking terminal 05 which extends at right angles thereto into a cylindrically shaped chamber a formed through the handle and lined with a glass tube a. One end of said chamber a is closed by the plate I) and the other end by a plate f and said plate f has a short arm 9 extending therefrom parallel to the arm 0. The dill'erence in length of said arms 0 and g is suflicient to enable them to be respectively placed in contact with the engine cylinder and the spark-plug terminal, as indicated in Fig. 1.

A sparking terminal, consisting of a pointed screw it is threaded in the plate f, in alinement with the terminal (I, said screw having a head 71/ and being adapted to be adjusted, so that its pointed end may be moved into contact with the pointed end of the terminal d, or to within a short distance therefrom, to provide a spark-gap of suitable length therebetween, as shown in- Figs. 1 and 4. The handle-and holder on is of wood, or other insulating material, so that the contact arms and terminals are insulated from each other, andcthe handle is also protected from the terminals by the glass tube (1.

If the ends of the tube e are tightly closed, so that the spark gap is located in an air-tight chamber, as has been the case with prior devices, the passage of the sparks will consume the oxygen of the air, so that either a partial vacuum will. be created, or the amount oi. oxygen in the chamber will be so deficient that. the spark will be practically invisible. c

As in the construction, as thus far described, the plates 7) and f would tightly close the ends of the tube e, I avoid. the difficulty above referred to, and insurea suflicient supply of oxygen to said tube, by providing one or more vent aperturesri in said plates 7) and f in the portions thereof opposite the interior of said tube. Air may thus pass readily into said tube e, sothat sufiicient oxygen will be supplied thereto to insure the formation of sparks at the terminals which will be suifieiently yellow to enable them-to be readily observed. These 5 apertures i are so arranged that they do not permit the passage oi light directly to the spark gap.

To enable the spark at the spark'gap tobe observed, I provide the holder With a circular sight aperture a which extends therethrough with its center line at right angles to-the center line of the terminals (1 and h at the middle of the spark gap. As either end of this aperture a may be readily a h and d, and will be shielded from the out- In use the device is placed in the positionof Fig, 1, and, if-the plugis'sparking at its points, sparks'will also pass across the spark gap between the ends of the terminals side light, sothat they may be readily observed through either sight hole a which may be used most conveniently.

By making the terminal h adjustable the length of the spark-gap may bevaried to conform to currents oi different strengths or conditions-ofuse, which is very'des rable, as

l thesev terminals should be separated (far enough to enable the sparks to be readily seen and yejpfnust not be separated so far mm 02 this patent may he obtained for that the spark will not readily jump the l v I claim:- l. A jump-spark tester, comprising a holder of insulating material having a sight aperture therethrough, a transparent tube extending through said holder transversely of said sight aperture, metal plates connected to said holder and closing the ends of said tube, conductors mounted in said plates and extending oppositely Within said tube, so that their ends are in sparking relation and contact arms extending from said plates beyond the holder substantially as described.

2. A jump spark tester comprising an insulating holder having a transparent insulating tube extending therethrough, metal plates connected to said holder. and closing the ends of said tube, and contact arms extending from said plates having sparking terminals within the tube, said plates having vent apertures leading to the interior of said tube and said holder having a sight aperture directed to the spark gap, and constructed otherwise to shield said spark gap from the direct rays of light thereto, substantially as described.

In testimony'whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

v PERCY B. SPOFFORD. lVitnessesi L. H. HARRI AN, H. B. DAVIS.

five eentaeach, by addressing the "Commissioner of Patents.

Waahimgton, &. 6." 

